1. Technical Field
The present invention relates generally to a probe, and more particularly to a probe module which supports loopback test.
2. Description of Related Art
To test if every electronic component of a device-under-test (DUT) is electrically connected correctly, a widely used method is to apply a probe card between a tester and the DUT, wherein the probe card is functioned as a transmission interface which transmits test signals and power signals therebetween.
However, with the advancement of digital technology, the operating speed and the signal throughput of electronic devices are increasing, which makes the frequencies of test signals generated by processors of the tester insufficient to satisfy the demand for testing such electronic devices. In order to solve such problem, a DUT may therefore be utilized to generate high-frequency signals by itself, and those signals are then transmitted back to the DUT again via a probe card to perform testing.
As shown in FIG. 1, a conventional probe card has a plurality of relays 72 provided on a printed circuit board (PCB) 70 thereof, wherein conductor patters on the PCB 70 are designed in a way that each relay 72 can be controlled to switch between signal paths of DC test signals provided by a tester 300 and that of high-frequency test signals provided by the DUT 400 for loopback test. In other words, the relays are used as signal path switchers. It is well known that, with longer signal path, there would be higher inductance generated thereon. In other words, since each of the signal paths of the high-frequency test signals is quite long, which starts from a probe module 80, sequentially goes through the PCB 70, one of the relays 72, one of capacitors 74, and finally goes back to the probe module 80 through another one of the relays 72 and the PCB 70 again, test signals of higher frequency would lead to higher inductance generated along the signal paths, and therefore cause higher resistance as well. As a result, some of the high-frequency test signals may not be successfully transmitted to the DUT 400, which obviously hinders the process of test.